MAPPING OF A LOCUS CONTROLLING RESISTANCE TO ALBUGO-CANDIDA IN BRASSICA-NAPUS USING MOLECULAR MARKERS

White rust, caused by Albugo candida, is an important disease of crucifers, vegetables, and oilseeds in many countries. A backcross population, BCP2, as well as F-1-derived doubled-haploid (DH) and F-2 populations obtained from the same single F-1 plant, produced from the cultivar Major X Stellar, were used to study the genetic control of resistance to white rust in Brassica napus. The control of resistance to white rust in this cross was attributed to a dominant allele at a single locus, designated ACA1. Other loci may be involved in the control of the intensity of sporulation of the fungus in the plant. The ACA1 locus was mapped with respect to restriction fragment length polymorphism (RFLP) loci in the F1DH population. Linkage between the ACA1 locus and nine RFLP loci was observed on linkage group 9 of a B. napus RFLP linkage map.